OBJECTIVE: The purpose of this study was to evaluate the anticancer potential of dietary omega-3 supplementation to reduce induced intestinal preneoplastic lesions in Wistar rats. METHODS: A total of 58 11-week-old male Wistar rats (Rattus norvergicus, albinus variety, Rodentia) were distributed into two groups: a control group (n=25) and an omega-3-treated group (n=28). Aberrant crypt foci were induced by 1,2-dimethylhydrazine. Tissue incorporation of the supplemented omega-3 fatty acids was evaluated by determining the fatty acid profiles of intra-abdominal fat and the liver with gas chromatography. RESULTS: The omega-3 group presented lower weight and lower food intake (p<0.05) than the control group. The number of aberrant crypt foci decreased 55.34% in response to omega-3 supplementation. Foci with more than three crypts decreased 57.14% between weeks 13 and 28. There was no statistical difference for the docosahexaenoic acid content in the liver of the omega-3 group between week 6 and weeks 13 and 28. CONCLUSION: These results suggest that omega-3 may slow the progress of colorectal carcinogenesis.